1. Field of the Invention
This invention relates to a bleach mixture which may be added to a detergent composition or which may be additionally added to a wash liquor to enhance the bleaching effect, particularly at a temperature in the range from 30.degree. C. to 60.degree. C.
Known bleaches generally consist of a combination of a perhydrate, more especially sodium perborate, with a bleach activator, a bleach activator being understood to be a hydrolyzable compound which forms per-acids with the perhydrate in aqueous solution. Since mixtures of the two components react with one another even in the presence of small quantities of atmospheric moisture and thus suffer losses of activity, the powder particles of the individual components have to be spatially separated from one another, which may be done by mixing with relatively large amounts of powder-form extenders or diluents and/or by coating one or both components. Where the components are added to a detergent, the detergent itself may act as a release agent and extender. In that case, however, the user is no longer able to dose the bleach component individually as required or, for example in the washing of delicate fabrics, to dispense with a bleach component altogether.
2. Discussion of Related Art
The coating of one of the bleach components is a relatively involved process. In addition, individual coating materials can delay or complicate the dissolution and release of the bleach component in cold or moderately warm water. Further, it has been found that standard parting agents and extenders, for example sodium sulfate, sodium carbonate or disodium hydrogen phosphate, are attended by considerable disadvantages, irrespective of whether they are present in anhydrous, partially hydrated or completely hydrated form. The salt mixtures containing water of crystallization tend to cake when temperatures of 30.degree. to 35.degree. C. are reached or exceeded during storage or transport. Although mixtures free from water of crystallization are stable in storage, they tend to cake and clump in the dispensing compartment of standard domestic washing machines, with the result that residues are left in the dispensing compartments.